Electrical transformer.



No. 891,496. PATENTED JUNE 23, 1908. A. R. LUSGHKA. ELECTRICAL TRANSFORMER.

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m m m N [Maggy jiuav (0r No. 891,496. PATENTED JUNE 23, 1908.

- A. R. LUSOHKA.

ELEGTRIGAL'TRANSPORMER.

APPLICATION FILED DBO. 11, 1905- v 2 nnms-snnm 2.

25 amount of wire in t 85 ously from one end to theother of 50 or to the core,

cuit where it isintendedthat it shall flow.-

AUGUST R. LUSOHKA, OF RIVER FOREST,

ILLINOIS, ASSIGN OR TO WESTERN ELECTRIC COM- PANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

ELECTRICAL TRANSFORMER.

Specification of Letters Patent.

Patented June as, 1 908.

Application filed December 11, 1906. Serial No. 291,266.

To all whom it may concern:

Be it known that I, AUGUST R. 'LUsoHKA, a citizen of Switzerland, residing at River Forest, in the county of Cook and State of 5 Illinois, have invented certain new and useful Improvements in Electrical Transformers, of which the following is a. specification.

My invention relates to an apparatus for converting or transforming low potential current into alternating current of high potential, and has to do more particularly with that type of converting or transforming apparatus commonly known as induction or spark coils, 'wherein two or more coils or windings of wire are arranged in fixed relation to each other, the conversion or transformation being brought about by electromagnetic inductive action between the windingsl. y principal object is to provide an apparatus of this character of simple and relatively inexpensive construction, of particular efficiency of operation, and, with a given expenditure of energ requiring a minimum liesecondary winding for a iven length of spark.

nduction coils as commonly constructed comprise a laminated iron core, over which is wound a primary winding of relatively coarse copper wire, and over this a secondary Winding o relatively. fine copper wire, the windings and the core being appropriately insulated from each other. The secondary winding is usually either wound continuthe space "reserved for it, or is divided into a plurality of narrow disk-shaped sections serially connected, and arranged adjacent to each other with insulating partitions between, the sec.-

40 tions and their partitions practically fillin the winding space; One of the principal di ficulties encountered in the construction of coils of this'character is the liability of the high potential which they generate breaking down the intervening insulation and causing the current to flow in a short circuit between adjacent? or even widely separated, convolu tions or sections of the secondary winding, or from the secondary to the primary winding instead of in the external cir- It has-also been found that where a certam potentialis generated by a single section of a sectionally wound coil, the potential, as measured by the length of the spark produced, does not increase in the expected ratio when the sections of the coil are electrically coupled together. This peculiarity has been attributed commonly, and, it is believed, properly to a supposed lack of synchronism in the development of the induction currents in the various sections, as a re sult of which the currents are out of phase and tend to oppose, or, at least, not to assist each other.

It has been In particular object to produce a coil in which a high degree of insula tion betweenthe portions of the secondary winding having a great difference of potcntial, and between the secondary winding and the rimary winding shall be obtained, not by t e interposition of massive and expensive insulating partitions, as has ordinarily been the custom, but rather by a peculiar arrangement of the parts of the coil; and at the same time, by this arrangement of parts, to secure such resonance, or synchronism in the development of the induced currents in the different sections of the winding that the effects will strongly reinforce each other and produce the maximum potential for a given expenditure of energy and length of wire in the winding. This result, generally speaking, I accomplish by arranging the secondaryv windings of my induction coil in sections symmetrically dis osed in the magnetic field of force produce by the rimary winding, and by arranging the convo utions of the-sections to recede progressively from each other, and from the primary winding and core, as the potential of the current generated in them increases, the bases of the sections preferably adjoining in approximately the plane of the center 0 convolutions may be intersected by the maximum number of lines of force.

In the preferred embodiment of my invention illustrated and described herein the secondary winding is in the form of two s mmetrical hollow truncated cones with t ieir apexes meeting in the plane of the longitudinal center of the core.. As a result of this arrangement, the

the magnetic held in order that the portion of the secondary winding closest the primary and the core is 1 nearest zero potential, while the terminals of the Winding where the potential is highest are the most remote from each other and from-the core; the current induced in the sections of the secondary winding are electrically symmetrical and in resonance, and thus additive in their effects, the resultant potential being much higher than would be obtained if the electrical inductive effects a peared in the sections at even very slight y difi'erent times; the sections of the secondary winding are located in the most advantageous position in the field of force, the angle of divergence of the sections from the core and from each other being such as to bring the convolutions within the greatest number of lines of force; and the turns of wire in the secondary are eliminated, which heretofore have been detrimental both in developing dissynchronous currents which interfere with the main induction currents, and in damping down the main currents by the resistance which the Y interpose, the total effect of the coil thus eing increased, while its cost is lessened. u

l will describe my invention more particularly by reference to the accompanying drawings, wherein Figure 1 is a front elevation in central section of an induction coil embodying my invention; Fig. 2 is an end elevation thereof; Fig. 3 is a diagrammatic view of the circuits of the coil, including the usual current generating and circuit controlling appliances; and Fig. 4is a graphic representation of the magnetic circuit. of the coil, showing the relation of the magnetic lines of force to the windings. In the embodiment of my invention illustrated, the induction coil roper is mounted upon a base 1 constructed of suitable material, such as wood, insulating fiber, or the like. Generally speaking, the induction coil comprises a core 2, consisting of a bundle of soft iron wire, a primary winding 3, wound upon the core and separated from it by an insulating tube 4 of paper or the like, a secondary winding 5 surrounding the primary and separated from it by a heavy insulating tube 6 of micanite or like material having high insulating'qualities, and spark terminals 7 and 8, connected with the ends of the secondary winding, the primary winding being also brought out to suitable terminals, 9 and 10. The various parts of the induction coil proper, as enumerated, are sup orted upon two end heads 11 and 12, prefera ly of wood, mounted u on the base 1 which, with an in closing shel 13 of hard rubber or like insulating material surrounding the secondary winding and supported upon the end heads, form a containing and protecting case for the induction coil ro er. The s ark terminals 7 and 8, with w ic the ends 0 the secondary winding are connected, ma comprise the usual electrodes consisting o a flat plate and a pointed tip of metal supported u on metal rods adapted to slide through hea s or posts of metal. The heads or posts are mounted ,ized to the fullest extent in the upon pillars of insulating material supported in a suitable manner, as shown, upon-opposite ends of the inclosing and protecting case. To produce the best distribution of the magnetic lines of force 1 construct my coil with the core 2 of considerable length, and adapted to project beyond both the primary and secondary windings. The primary winding is preferably wound over about two-thirds the length of the core, leaving approximately one-sixth of the length of the core pro'ecting beyond the winding at each end. T e primary winding, as shown, is in two layers, and both ends of each layer are preferably brought out separately to the bindin posts 9, 10, mounted upon the heads of cy inders 14 and 15, of insulating material. These cylinders project from the end heads, 11 and 12, and are secured thereto in any suitable manner, as by the rings 16, and serve to inclose and protect the portions of the core and the associated primary winding and insulating tubes which project beyond the end heads. From the binding posts, 9, 10, the connections of the primary winding may be extended by means of conductors as shown, to the binding posts, 17, 18, mounted on the base 1.

In accordance with my invention, instead of Winding the secondary winding to entirely fill the secondary winding space, either as a continuous winding or in the form of a number of disk-shaped sections insulated from each other and serially connected, as has been the practice heretofore, I arrange the secondary winding in the form of two sections disposed symmetrically with res ect to the magnetic field, and occupying on y a relatively small portion of the winding space available.

As shown in Fig. 4, which is a chart illustrating the distribution of the ma netic lines of force as observed in a'core suc as I em ploy in my induction coil, it will be seen that the lines emanate not only fromthe ends of the core, but from practically its entire length, being distributed well down towards the longitudinal center of the core. Those lines which escape from that art of the core encircled by the primary win ing are usually known as leakage lines, and in induction coils as ordinarily constructed are not utilroduction of inductive effects in the secon ary winding. In order to arrange my seconda winding in the most favorable osition wit respect to the magnetic field, construct itwit a narrow base having its center resting approximately at the magnetic center of the core where it will be in position to be intersected by the maximum number of the lines of force to insure the proper insulation from each other and from the core of the convolutions of the coil having a large difference of potential, I make the winding in sections,

and so dispose the sections that their convolutions progressively recede from each other and from the core, the separation increasing as the potential difference increases; and in order to insure the synchronous generation of the inductive currents in the two sections I arrange them symmetrically with respect to the magnetic field of force. When these conditions are satisfied, theresult, in the resent instance, is a secondary winding 5 o substantially the form of two hollow symmetrical truncated cones centrally perforated and placed with their apexes meeting in the )lane of themagnetic center of the core and t ieir axes coinciding with 'the longitudinal axis of the core.

One coil which I have built in accordance with the principles of my invention, and which I have found extremely efficient in )ractice', is constructed as follows: The core 18 made of abundle of No. 18 gage soft iron wire surrounded by a paper tube, on which is wound the primary winding consisting of two layers of 150 turns each of No. 13 co per wire, the primary winding covering a out two-thirds of the length of the core. The core with the primary winding upon it is placed within a tube of micanite having walls approximately one-fourth inch thick, at the longitudinal center of which the secondarywinding is supported. The secondary winding consists of two sections of the truncated conical form described, each section being wound with approximately twenty-five thousand turns of No. 29 insulated copper wire, the two sections bein arranged with their apexes together, and iaving their windings serially connected. In windin the secondary coil I have found it desirabTe to place a single thickness of oiled paper over each layer as it is wound, the paper preferably slightly overlapping the layer of wire at both sides, as indicated in Fig. l of the drawing by the long light lines, alternating with the heavy short lines, which indicate the la ers of wire. To still further increase the insulation of the secondary winding, I find it convenient to fill in the space about it with an insulating substance such as Vaseline, indicated by the reference character 19. On account of the I eculi'ar shape of the secondarv winding I fin it convenient to construct the end heads 11 and 12 generally to conform thereto, primerikyin order to lessen the space around the coil to be filled with the insulating material 19 and for the same reason I have shown in the present instance a ring or band 20 of triangular cross-section encircling the secondary coil within the inclosing shell 13. The end heads 11 and 12,'for the reason just indicated, are of substantially truncated conical form, the summit of the cone being directed inwardly, and the base being hollowed out as shown.

In its operation, the induction coilof my invention may be connected in a circuit as shown in Fig. 3, wherein one end of each of the two rimary windings is shown to extend by con uctors 21 and 22, to the middle points of two double-throw knife blade switches 23 and 24, while the other ends of the two primary windings extend by way of conductors 25 and 26, to two outer contacts 27v and 28 res ectively, of a double-throw switch 29, eacli of said contacts being also connected to the diagonally opposite outer contact of the switch. The middle points of this switch, which communicate with the knife blades, are connected through the medium of conductors 30 and 31, with a battery 32 or other source of electrical energy, and a device such, for instance, as a Welmelt interrupter for effecting a rapid interru tion of the circuit, indicated diagrammatica ly in the drawing, and designated by the reference character 33. The right-hand ends of the two primary windings are also connected, as indicated, by way of conductors 24 and 25 respectively with the two alternative contacts of the two singlespole. double throw switches-23 and 24. With the apparatus connected as described, the current flows from the source 32 through the interrupter 33 and by way of the double-pole doublethrow switch 29'in either one direction or the 5 winding only will be connected in circuit.

As the interruptions in the primary circuit cause the current therein to increase and diminish, the magnetic lines, as indicated in Fig. 4, expand and contract, and in so doing cut the convolutions of the secondary winding and generate therein the electro-motive forces which, being added together, cause a discharge to pass between the secondary terminals 7 and 8. As the two sections of the secondary winding are arranged symmetrically in the field of force, the impulses generatedtherein are synchronous and in phase, and consequently reinforce each other. Moreover, as the two sections are of relatively narrow cross-section, and also lie in a position in the field of force wherein the distribution of the lines is relatively uniform, the impulses in each section are not opposed and interfered with by dissynchronous inipulses developed in other convolutions of the same section. As a result of this the electromotive force developed in my induction coil,

and consequently the sparking distance between the secondary terminals, is unusually great; while the lower Ohmic resistance of the secondary arising from the smaller numl ber of turns required, and consequently less length of wire, results in a larger current, flow. As indicating the relative efliciency of my coil, I have observed that a secondary 1 of 90,000 turns of wire wound in the ordinary 1 way developed an electro-motive force capable of causing a discharge between its terl minals when the separation between them i was approximatel twelve inches, while an; induction coil bui t in accordance with Iny invention, and having a secondary of 50,000 1 turns gave a fourteen inch discharge, thei general conditions with respect to the, core and primary winding, and the primary current employed being the same in both. I claim: 1. An induction coil comprising an eloni gated core of iron wire, a primary Winding i thereon, covering only part of the length of said core, and a secondary winding about said primary winding inthe form of two holf low truncated cones with their a )exes meeting 5 at approximately the center oi the core, the planes of the bases of said cones intersecting the core at some distance from its ends. l 2. An induction coil, comprising a core of small iron wires, an insulating tube inclosing the same, a primary winding of relatively coarse wire wound upon said insulating tube, a second msnlatmg tube about said primary winding, a secondary winding comprising their small ends meeting at substantially the longitudinal center of the core, and truncated-conical end heads for said coil adapted to nest with said sections.

4. An induction coil, comprising a core, a

primary winding thereon, a secondary winding about said primary winding consisting of two hollow truncated-conical sections with their small ends meeting at substantially the longitudinal center of the core, truncatedconical end heads for said coil adapted to nest with said sections, and an insulating substance interposed in the space between said heads and sa d sections.

AUGUST R. LUSCHKA. Witnesses:

E. F. BEAUBIEN, R. W. INGERSOLL. 

